1. Field of the Invention
The present invention relates to a silicon carbide substrate, a silicon carbide ingot, and methods for manufacturing the silicon carbide substrate and the silicon carbide ingot, and more particularly to a silicon carbide substrate and a silicon carbide ingot capable of improving a yield of a semiconductor device having silicon carbide as constituent material, and methods for manufacturing the same.
2. Description of the Background Art
Conventionally, a study has been conducted on silicon carbide as next-generation semiconductor material which replaces silicon. As a method for manufacturing a substrate made of silicon carbide, there has been a known method of, for example, growing a silicon carbide layer made of single-crystal silicon carbide on a seed substrate through a sublimation method to form a silicon carbide ingot and slicing the silicon carbide ingot. For example, Japanese Patent Laying-Open No. 2004-323348 (PTD 1) discloses a method of preparing a seed substrate with a growth plane which is a (0001) plane (so-called c-plane) or a plane having a predetermined off angle with respect to the c-plane, and growing a silicon carbide layer on the growth plane. Further, in the silicon carbide ingot formed through such a method, a region with a crystal growth through a spiral growth (so-called a facet region) and a region with a crystal growth through a step-flow growth along steps of a crystal are formed.
There has been a problem that it would be difficult to sufficiently improve a yield when a semiconductor device is manufactured with use of the silicon carbide substrate obtained by the conventional method of forming a silicon carbide ingot and slicing the silicon carbide ingot.